Rotors for multi-stage axial flow compressors or turbines



Jan. 15, 1963 D. E, BUCKINGHAM 3,073,567

ROTORS FOR MULTI-STAGE AXIAL FLOW COMPRESSORS OR TURBINES 2 Sheets-Sheet 1 Filed Sept.- 4, 1959 INVENTOR bavno a. J. Bocnnemm BY w I a, Waywa- ATTOQNEQ Jan. 15, 1963 J, BUCKINGHAM 3,073,567

ROTORS FOR MULTI-STAGE AXIAL FLOW COMPRESSORS OR TURBINES 2 Sheets-Sheet 2 Filed Sept. 4, 1959- lNv E-NI'OR I Dawn 5. J. Bomnsnm Amanda 3,073,567 ROTORS FOR MULTI-STAGE AXIAL FLOW COMPRESSORS R TURBINES David Edwin James Buckingham, London, England, as-

signor to D. Napier & Son Limited, London, England, a

company of Great Britain Filed Sept. 4, 1959, Ser. No. 838,342 4 Claims. (Cl. 253-39) This invention relates to rotors for multi-stage axial flow compressors or turbines.

For reasons of lightness and to facilitate manufacture it is a common practice to build up such rotors from several sections which are fitted together end to end. In such rotors two main requirements have to be considered namely resisting the large centrifugal forces produced at high rotational speeds by the masses of the rotor blades and other rotating parts, and transmitting the drive from one section of the rotor to the next. i

It is an object of the invention to provide a rotor built up from a plurality of sections which is of particularly light and simple construction.

According to the present invention, the rotor blades are mounted in grooves formed in the peripheries of discs which resist centrifugal forces, and the bladeplatforms or the peripheries of the discs are provided with projections which enter notches in annular hoops inserted between adjacent rings of blades and which transmit torque from one ring of blades to the next.

Since the webs of the discs have to resist only centrifugal forces and do not have to transmit any torque, and since the hoops which transmit the torque have only to resist centrifugal forces arising from their own masses, which are relatively small, the discs and the hoops can all be of light construction.

In order to provide a seal to prevent leakage of gas from the annular blade channel into the hollow interior of the rotor or vice versa, annular sealing members may be provided between adjacent blade rings, which sealing members underlie the corresponding hoops and extend beneath the platform portions of the adjacent blades.

The invention may be performed in various ways and two particular forms of axial flow compressor rotor embodying the invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a longitudinal section of the upper half of one form of rotor embodying the invention with the central portion broken away and omitted;

FIGURE 2 is a fragmentary developed view of a portion of the surface of the rotor of FIGURE 1 showing parts of two consecutive blade rings;

FIGURE 3 is a fragmentary section of the periphery of one rotor disc taken on the line IIIIII in FIGURE 2;

FIGURE 4 is a fragmentary section of the periphery of the rotor disc of FIGURE 3 with a blade in place, taken on the line IV-IV in FIGURE 2;

FIGURE 5 is a view similar to FIGURE 2 but showing a modified form of disc and blade construction;

FIGURE 6 is a fragmentary section of the periphery v of one modified rotor disc taken on the line VI--VI in FIGURE 5; and

FIGURE 7 is a fragmentary section of the periphery of the rotor disc of FIGURE 6 with a blade in place taken on the line VIIVII in FIGURE 5.

The rotor shown in FIGURES 1 to 4 inclusive is for an axial flow compressor of an aircraft power unit. It consists of a central tube 10 of light construction extending between an inlet end disc 11 and an outlet end disc 12. The forward end of the tube 10 is provided with a flange portion 13 which fits into the tubular portion 14 extending forwardly from the inlet end plate 11.

' the. tube 10 toward the right until the axially presented rings are annular sealing members 38.

Interior splines 14a, in tubular portion 14, intermesh with exterior splines 1 3a on the flange 13, to prevent relative rotation between tube 10 and portion '14. The rear end of the tube 10 passes through the outlet end disc 12 and.

is provided with a washer 15 which abuts against the rear .1 face of the end disc 12, and a nut 16 which is screwed up tight against the washer 15. The tube 10 with its flange 13, the washer 15 and the. nut 16 clamp the whole rotor assembly firmly together. nut 16 at the right hand end of the tube 10 tends to draw rearwardly extending tubular portion 19 which is sup-- ported in a ball bearing 20 which is in turn supported in a rigid mounting 21. The tubular portion 19 is also provided with splines 22 through which a drive can be transmitted to the compressor rotor from a turbine. The front end disc 11 carries blades 23 forming the first compression stage of the rotor, and the outlet end disc 12 carries blades 24 constituting the final compression stage of therotor.

-Disposed at intervals along the central tube 10 are.

blade-carrying annular discs 25. Each assembly consisting of a disc and the blades mounted thereon is termed herein a blade ring. Each disc comprises a bored boss 26 through which the central tube 10 passes freely, and. a thickened rim portion 27 provided with inclined grooves 28 (see FIGURE 2). The grooves are conveniently formed by broaching, and are appropriately shaped. in cross-section to receive root portions 29 of the blades 30 of intermediate rotor stages. Stator blades 40 are mounted in a housing 41 and arranged downstream of each ring of rotor blades. 1 a

Each rotor blade 30 consists of an aerofoil portion 33, a root portion 29 as referred to above which is received in one of the grooves 28, and a platform portion 34 intermediate between the aerofoil portion 33 and the root portion 29. r

The axial thickness 0 of the thickened rim portion 2 7 is greater than the axial length b of the platform portions 34 of the blades, so that between the platform portion 34 the thickened rim portion extends axially beyond the plat form portions, providing projections 31 extending forwardly and corresponding projections 32 extending to? wards the rear.

The projections 31, 32 of the discs 25 enter notches formed in torque-transmitting hoops 35. Each hoop 35 has notches 36 in its forward edge and notches 37 in its rearward edge. The forward projections 31 on the disc 25 immediately to the rear of each hoop 35 enter the notches 37, while the rearward projections 32 of the disc in front of the hoop member enter the notches 36.

The edges of the hoops 35 between the notches 36, 37 abut against the adjacent ends of the platform portions 34 of the blades, thereby serving to locate the blades in the axial direction.

Underlying each hoop and extending beneath the platform portions 34 of the blades of the two adjacent blade These are in the form of hoops each fitted in between adjacent discs 25 underneath the corresponding torque-transmitting hoops 35, with their forward and rearward edges touching the end surfaces of the adjacent blade roots 29 and the portions of the discs 25 between these surfaces.

In operation, the centrifugal forces due to the mass of Patented Jan. 15', 19 63 The tightening of the rotating blades 30 are resisted practically entirely by the webs 25 of the discs 25 which, since no torque is transmitted through them, can be made quite thin and light. Torque is transmitted from one blade ring to the next through the said projections 31, 32 and the intervening ho p 3 In the modification shown in FIGURES 5 to 7, the projections are constituted by the axial extremities 41 and 42 of the platform portions 43 of the rotor blades 44. In this case the axial thickness c of the thickened rim portion 45 of the discs 46 is less than the overall axial length d of the platform portions 43, whereby the said extremities 41 and 42 project beyond the rim portions 45 of the discs. These extremities or projections 41 and 42 engage into notches 47 and 48 formed respectively in the rear and front edges of torque-transmitting hoops 49, which perform the same function as the hoops 35 of the FIGURES 1-4.

It will be observed that in both embodiments described the construction is very simple. Each blade ring consists of a disc made from a single piece of material to which the blades are secured directly in grooves broached in the disc. The driving connections between the blade rings and the hoops utilize the projections that are obtained by making the thickened rim portions of the discs and the blades mounted thereon of different axial dimensions, so that no additional machining operations are required. Moreover, the torque is transmitted from one blade ring to the next at the most favourable place; i.e. at the maximum possible radius from the axis of rotation.

This is a continuation-in-part from my application Serial No. 753,331, filed August 5, 1958, now abandoned.

What I claim as my invention and desire to secure by Leters Patent is:

1. A bladed axial flow rotor comprising a plurality ofaxially spaced discs, each disc having an ntegral circular rim portion having oppositely facing parallel transverse end faces and provided with a plurality of substantially axial open-ended grooves extending between said end faces, a plurality of blades disposed in circurnferentially spaced relation around each of said rim portions, each of said blades having a platform portion and a root portion fitting in one of said grooves and each of said platform portions having oppositely facing parallel transverse end faces, the maximum axial dimension of each said rim portion between said end faces thereof being different from the maximum axial dimension of said blades between said end faces of said platform portions, said platform portions and said rim portions together providing, by reason solely of said difference in said axial dimensions thereof, a plurality of circumferentially spaced projections extending forwardly and rearwardly, and torque-transmitting hoops each disposed between two adjacent discs, each hoop having a circumferentially notched forward edge and a circumferentially notched rearward edge, the notches in said edges receiving said projections in positive torquetransmissible relationship.

2. A rotor according to claim 1 which includes annular sealing members between adjacent discs, said sealing members underlying said hoops and extending beneath the platform portions of the blades disposed around said rims of said adjacent discs.

3. A rotor according to claim 1 in which said maximum axial dimension of said rim portion of each disc is greater than the said maximum axial dimension of said platform portions of the blades mounted on this disc, whereby said projections are constituted by portions of said rim portion lying between said blade-receiving grooves thereof.

4. A rotor according to claim 1 in which said maximum axial dimension of said rim portion of each disc is less than said maximum axial dimension of said platform portions of the blades mounted on this disc, said platform portions having parts projecting axially beyond said rim portion and said projecting parts constituting said projections.

References Cited in the file of this patent UNITED STATES PATENTS 1,545,495 Holzwarth "a July 14, 1925 1,793,468 Densmore Feb. 24, 1931 2,497,151 Clark Feb. 14, 1950 2,540,991 Price Feb. 6, 1951 2,689,682 Boyd Sept. 21, 1954 2,741,454 Eppley Apr. 10, 1956 2,763,462 McDowall et a1. Sept. 18, 1956 2,773,667 Wheatley Dec. 11, 1956 2,803,397 Gardiner Aug. 20, 1957 2,807,436 Hockert Sept. 24, 1957 2,825,124 Nichols et al Mar. 4, 1958 2,988,324 Sutters June 13, 1961 FOREIGN PATENTS 468,844 Canada Oct. 17, 1950 5 8,874 Belgium Apr. 15, 1953 155, 68 Australia Feb. 9, 1954 709,748 Great Britain June 2, 1954 723,813 Great Britain 1. Feb. 9, 1955 1, 17,727 France Nov. 2, 1954 

1. A BLADED AXIAL FLOW ROTOR COMPRISING A PLURALITY OF AXIALLY SPACED DISCS, EACH DISC HAVING AN INTEGRAL CIRCULAR RIM PORTION HAVING OPPOSITELY FACING PARALLEL TRANSVERSE END FACES AND PROVIDED WITH A PLURALITY OF SUBSTANTIALLY AXIAL OPEN-ENDED GROOVES EXTENDING BETWEEN SAID END FACES, A PLURALITY OF BLADES DISPOSED IN CIRCUMFERENTIALLY SPACED RELATION AROUND EACH OF SAID RIM PORTIONS, EACH OF SAID BLADES HAVING A PLATFORM PORTION AND A ROOT PORTION FITTING IN ONE OF SAID GROOVES AND EACH OF SAID PLATFORM PORTIONS HAVING OPPOSITELY FACING PARALLEL TRANSVERSE END FACES, THE MAXIMUM AXIAL DIMENSION OF EACH SAID RIM PORTION BETWEEN SAID END FACES THEREOF BEING DIFFERENT FROM THE MAXIMUM AXIAL DIMENSION OF SAID BLADES BETWEEN SAID END FACES OF SAID PLATFORM PORTIONS, SAID PLATFORM PORTIONS AND SAID RIM PORTIONS TOGETHER PROVIDING, BY REASON SOLELY OF SAID DIFFERENCE IN SAID AXIAL DIMENSIONS THEREOF, A PLURALITY OF CIRCUMFERENTIALLY SPACED PROJECTIONS EXTENDING FORWARDLY AND REARWARDLY, AND TORQUE-TRANSMITTING HOOPS EACH DISPOSED BETWEEN TWO ADJACENT DISCS, EACH HOOP HAVING A CIRCUMFERENTIALLY NOTCHED FORWARD EDGE AND A CIRCUMFERENTIALLY NOTCHED REARWARD EDGE, THE NOTCHES IN SAID EDGES RECEIVING SAID PROJECTIONS IN POSITIVE TORQUETRANSMISSIBLE RELATIONSHIP. 